Northeast Seen Getting Balmier

NEW YORK -- New England's maple trees stop producing sap. The Long Island and Cape Cod beaches shrink and shift and disappear in places. Cases of heatstroke triple.

And every 10 years or so, a winter storm floods portions of Lower Manhattan, Jersey City and Coney Island with seawater.

The Northeast of recent historical memory could disappear this century, replaced by a hotter and more flood-prone region where New York could have the climate of Miami and Boston could become as sticky as Atlanta, according to the first comprehensive federal studies of the possible effects of global warming on the Northeast.

"In the most optimistic projection, we still end up with a six- to nine-degree increase in temperature," said George Hurtt, a University of New Hampshire scientist and co-author of the study on the New England region. "That's the greatest increase in temperature at any time since the last Ice Age."

Commissioned by Congress, the separate reports on New England and the New York region explore how global warming could affect the coastline, economy and public health of the Northeast. The language is often technical, the projections reliant on middle-of-the-road and sometimes contradictory predictive models.

But the predictions are arresting.

New England, where the regional character was forged by cold and long, dark winters, could face a balmy future that within 30 to 40 years could result in increased crop production but also destroy prominent native tree species.

"The brilliant reds, oranges and yellows of the maples, birches and beeches may be replaced by the browns and dull greens of oaks," the New England report concludes. Within 20 years, it says, "the changes in climate could potentially extirpate the sugar maple industry in New England."

The reports' origins date to 1990, when Congress passed the Global Change Research Act. Seven years later, the Environmental Protection Agency appointed 16 regional panels to examine global warming, and how the nation might adapt. These Northeast reports, completed about two months ago, are among the last to be released.

The scientists on the panels employed conventional assumptions, such as an annual — percent increase in greenhouse gases in the atmosphere. They conclude that global warming is already occurring, noting that, on average, the Northeast became two degrees warmer in the past century. And they say that the temperature rise in the 21st century "will be significantly larger than in the 20th century." One widely used climate model cited in the report predicted a six-degree increase, the other 10 degrees.

The Environmental Protection Agency summarizes the findings on its Web site.

"Changing regional climate could alter forests, crop yields, and water supplies," the EPA states. "It could also threaten human health, and harm birds, fish, and many types of ecosystems."

Yale economist Robert O. Mendelsohn is more skeptical. He agrees that mild global warming seems likely to continue -- but argues that a slightly hotter climate will make the U.S. economy in general, and the Northeast in particular, more rather than less productive. A greater risk comes from spending billions of dollars to slow emissions of greenhouse gases.

"Even in the extreme scenarios, the northern United States benefits from global warming," said Mendelsohn, editor of the forthcoming "Global Warming and the American Economy." "To have New England lead the battle against global warming would be deeply ironic, because it will be beneficial to our climate and economy."

The scientists on the Northeastern panels estimated that Americans have a grace period of a decade or two, during which the nation can adapt before global warming accelerates.

"We will face an increasingly hazardous local environment in this century," said William Solecki, a professor of geography at Montclair State University in New Jersey and a co-author of the climate change report covering the New York metropolitan region. "We're in transition right now to something entirely new and uncertain."

Compared with a century ago, the report notes, ice melts a week earlier on northern lakes. Ticks carrying Lyme disease range north of what scientists once assumed was their natural habitat. Moist, warm winters have led to large populations of mosquitoes, with an accompanying risk of encephalitis and even malaria.

"The present warming trend has led to another growing health problem," the report states, "in the incidence of red tides, fish kills and bacterial contamination."

Hot, dry summer months, the report continues, "are ideal for converting automobile exhaust ... into ozone." Because winds flow west to east, New England already serves as something of a tailpipe for the nation. The report notes that a study of ozone pollution and lung capacity found that hikers on Mount Washington, New Hampshire's highest peak, ended their treks in worse condition than when they started.

These findings are not definitive. Rising temperatures could exacerbate the effects of harmful ozone -- but anti-pollution laws are also cutting emissions.

"There is a little tendency to be alarmist in global warming studies," said Patrick Kinney of the Mailman School of Public Health at Columbia University. "We could keep ozone in check."